Biomedical subjects
Publications and source records attributed to Yoshihiro Edamoto.
A 36-year-old man fell from his bicycle and struck his lower abdomen on the end of the handlebar. Computed tomography (CT) showed a small bowel loop protruding into the subcutaneous fat layer of the abdominal wall. We present this case of handlebar hernia, a rare type of traumatic abdominal wall hernia, and the usefulness of CT in diagnosing such injuries.
Major etiologic factors associated with human hepatocellular carcinomas (HCCs) include infection with hepatitis C (HCV) and hepatitis B virus (HBV), excess alcohol intake and aflatoxin B(1) exposure. While the G-->T p53 mutation at codon 249 has been identified as a genetic hallmark of HCC caused by aflatoxin B(1), the genetic profile associated with other etiologic factors appears to be less distinctive. In our study, we screened HCCs resulting from HCV infection (51 cases), HBV infection (26 cases) or excess alcohol intake (23 cases) for alterations in genes involved in the RB1 pathway (p16(INK4a), p15(INK4b), RB1, CDK4 and cyclin D1), the p53 pathway (p53, p14(ARF) and MDM2) and the Wnt pathway (beta-catenin, APC). Alterations of the RB1 pathway, mainly p16(INK4a) methylation, loss of RB1 expression and cyclin D1 amplification, were most common (69-100% of cases). There was a significant correlation between loss of RB1 expression and RB1 methylation. All 24 HCCs with RB1 promoter methylation lacked RB1 expression, while none of the 67 cases with RB1 expression exhibited RB1 methylation (p < 0.0001), suggesting that promoter methylation is a major mechanism of loss of RB1 expression in HCCs. Alterations of the p53 pathway consisted mostly of p53 mutations or p14(ARF) promoter methylation (20-48%). Mutations of the p53 gene were found at a similar frequency (13-15%) in all etiologic groups, without any consistent base change or hot spot. Mutations of beta-catenin were found in 13-31% of cases, while no APC mutations were detected in any of the HCCs analyzed. With the exception of only 3 of 39 cases (8%), cyclin D1 amplification and beta-catenin mutations were mutually exclusive, supporting the view that cyclin D1 is a target of the Wnt signaling pathway. Overall, the RB1, p53 and Wnt pathways were commonly affected in HCCs of different etiology, probably reflecting common pathogenetic mechanisms, i.e., chronic liver injury and cirrhosis, but tumors associated with alcoholism had more frequent alterations in the RB1 and p53 pathways than those caused by HCV infection.
We investigated the relationship of infection with hepatitis B virus (HBV) and hepatitis C virus (HCV) to p53 mutation in hepatocellular carcinomas (HCC) from six countries, including Japan, China, Korea, Vietnam, Spain, and the Unites States. For this purpose, we used formalin-fixed, paraffin-embedded liver tissues obtained from 449 patients with HCC to detect the viral and p53 genes by polymerase chain reaction (PCR). HBV was the most prevalent in Korea (69.1%), China (66.1%), Vietnam (60.5%), and Spain (38.6%). In contrast, HCV was the most prevalent in Japan (59.8%) and in the United States (41.5%). Type C of HBV was the most common genotype (78.6%) encountered in HCC in these countries. Importantly, among 125 intrahepatic HBV DNA-positive patients, 44 (35.2%) were serologically negative for HBsAg (occult hepatitis B). Based on PCR, immunohistochemical, serological, and clinical findings, 4.8% of HCC patients were diagnosed with non-B, non-C. A point mutation at exon 7 of p53 was detected in 20 of the 239 HCC samples examined, including those from 9 Chinese, 5 American, 2 Japanese, 2 Korean, and 2 Spanish patients, respectively. Interestingly, a point mutation with an amino acid substitution at codon 251 (Ile-->Asn) was detected frequently in 11 of 20 (55%) cases. A specific mutation induced by Aflatoxin B1 at codon 249 was seen in two patients, both Chinese. Our results suggest that genotype C of HBV may play an important role in hepatocarcinogenesis in different geographic regions, and that in situ detection of HBV genomes could be important for clarifying the agent(s) of unknown etiology related to HCC.